Posted
by
timothyon Thursday March 29, 2012 @12:38PM
from the not-just-in-kansas-anymore dept.

astroengine writes "For the first time, huge solar tornadoes have been filmed by NASA's Solar Dynamics Observatory (SDO) swirling deep inside the solar corona — the sun's superheated atmosphere. But if you're imagining the pedestrian tornadoes that we experience on Earth, think again. These solar monsters, measuring the width of several Earths and swirling at speeds of up to 300,000 kilometers (190,000 miles) per hour, aren't only fascinating structures; they may also trigger violent magnetic eruptions that can have drastic effects on our planet. 'These tornadoes may help to produce favorable conditions for CMEs to occur,' said Xing Li, solar physicist at Aberystwyth University and co-discoverer of the phenomenon."

No, you are making the mistake. The conversion in units needs to take into account the precision of the original number to determine where it should be rounded. I doubt the determination of the top speed is within 4,000mph, so the 190K number is better than the 186K number. 200K might even be more fair, but it depends on the original data. Unfortunately, the units conversions are typically done by people who don't understand the concept of significant digits, let alone have any information about how precise the original number really is.

Oops - this was just a reference to equivalencies, not the actual speeds. Mea culpa.

And yes - with conversions comes the question of precision. If they'd said 3x10^6km/hr, it would've meant anywhere from 250,001km/hr - 350,000km/hr. A conversion to read as 2x10^6mi/hr would be fairly sloppy IMHO, but within bounds.

Still - it'd be interesting to know if relativistic effects are present.

They always are, the only question is how measurable they are. A rule of thumb I learned in a physics class is the relativistic effects become important at 10% of the speed of light. Of course, 'important' is a relative term.......

When you're talking about approximate speeds near the speed of light it's usually safer to report lower figures. Rounding down is better than rounding up. Otherwise you might cause unnecessary excitement...

Well, that's reasonably close. Remember also that they're talking about per hour rather than per second. (You probably did, but I didn't for a second or so...and thought there must be some other mistake.)

Angular velocity is a better way to measure the speed of a spinning object, because it factors out the object's diameter. Sure, 300Mm per hour sounds fast, but for an object that size, it's probably not a very impressive angular velocity.

Angular velocity might not convey much either by itself, and even if the angular velocity is unimpressive, the linear velocities involved might still be significant. 40,000 RPM is slow and unimpressive for something like a dentist drill, but say for a pulsar that is 20 km across, that has the surface going 15% of c.

In this case if you assume it is 5 earth diameters across, and the edge is at 300,000 km/hr, you get an angular velocity of about 0.025 RPM, which might not mean much to most people. To put it

We don't measure the speed of terrestrial tornadoes or other cyclonic weather phenomenon with angular velocity. The angular velocity of a hurricane isn't that impressive either but the linear velocity of the wind surely is.

This, too, is extremely impressive speed even if the angular velocity is low. So what if it's rotating slowly, those winds still had to be accelerated to 300Mm/hr! That's impressive!

I wish it had said "Solar Monster Tornadoes" - there are so many more visual images possible that way. It's even better when combined with the Pedestrian Tornadoes mentioned in the summary. Wheee!I also wish it said "Tornados", but that's just because I live in the central part of the country.

Agreed. The Sun is just an incredibly large hot gas giant, not necessarily too different from Jupiter in many regards.

There are differences - magnetism plays a larger role since the Sun is made of plasma and not gas. There aren't too many objects in the solar system which can exert a tremendous gravitic influence on the Sun. Unlike Jupiter (or most planets, for that matter), the Sun's core is cooler than it's surface. The weather may have some different properties, but it's still weather.

I'm not contradicting the statement, but how do they know that? What sort of instrumentation did they use to take temperature measurements for the center? AFAIK it's still a reasonable debate as to the properties of our own earth's core, and we live ON IT. Does our distance from the sun (vs. our perspective of the earth) or another difference between the sun and our planet make one's core temperature measurable and the other's not? I'm not trolling. This is not my area of expertise, but I do think it's

What sort of instrumentation did they use to take temperature measurements for the center?

They can't measure it directly, obviously. The numbers quoted are those given by our best scientific models of the Sun's structure and its nuclear processes. Those models predict fairly accurately the properties and behavior that we *can* observe and measure from Earth and from our space probes, so they give us some reasonable degree of confidence that we're in the right ballpark when estimating a temperature for the

But if you're imagining the pedestrian tornadoes that we experience on Earth, think again.

My thoughts seeing this title: 'Monster Tornadoes are on the sun, OMFG we're gonna die.' I came down from the knee-jerk ridiculousness of course, but at no point did I think 'Hah, I survived the freak-o F3 that plowed through my area in June, this is nothing!'